Leetcode--Add to List 371. Sum of Two Integers

题目

Calculate the sum of two integers a and b, but you are not allowed to use the operator + and -.

Example:

Given a = 1 and b = 2, return 3.

不使用+ - 实现加法

思路

位运算来实现

代码

递归版本

class Solution {
public:
int getSum(int a, int b) {
if(b == 0) return a;
return getSum(a^b, (a&b)<<1);
}
};

非递归版

class Solution {
public:
int getSum(int a, int b) {
while(b)  {
int carry = a & b;
a = a ^ b;
b = carry << 1;
}
return a;
}
};